Synthesis Of Cycloaliphatic Epoxy Polysiloxane And Research On Its Modified Epoxy Resin

With the development of semiconductors and technology,electronic devices have become highly industrialized.As an important branch of electronic packaging materials,epoxy resin still faces the problems such as brittleness and relatively poor durability after forming three-dimensional network structures with cross-linking behavior,which cannot meet the application of high level products.Polysiloxanes are well promising solutions because of their excellent thermal stability,low polarity,flexibility and electrical insulation.However,due to the large difference in solubility parameters between polysiloxanes and epoxy resins,direct mixing tends to produce obvious phase separation and adversely affect the performance of the thermosets.The introduction of epoxy groups into the polysiloxane is an effective measure to improve its compatibility with epoxy resins,but how to design the epoxy value of epoxy-based polysiloxane to highly match the epoxy resin matrix through structural design is a tough problem,which is very important for improving the cross-linking density and component compatibility of epoxy resins.Therefore,in this study,a series of cycloaliphatic epoxy-polysiloxanes with different molecular weights and functionality were prepared by cationic ring-opening polymerization and hydrosilylation,by taking advantage of the flexible design of linear polysiloxane structure and molecular weight.By adjusting the epoxy value and structure to match with the resin matrix,the compatibility of silicon-based and carbon-based components was greatly improved,and the phase separation was effectively suppressed,which strengthened the overall performance of the modified epoxy thermosets.This study was aimed to expand the application field from traditional devices to LED electronic packaging materials.The main research contents are as follows:1.Preparation of cycloaliphatic epoxy polysiloxane and research on its modified DGEBA epoxy resin(E51)First,cycloaliphatic epoxy-polysiloxane CP(MH-co-DM)S_E55 was prepared by using octamethyl cyclotetrasiloxane(D₄),1,3,5,7-tetramethylcyclotetrasiloxane(D₄H),1,1,3,3-tetramethyldisiloxane(TMDS),and 1,2-Epoxy-4-vinylcyclohexane(EP-101)as raw materials.The chemical structures of CP(MH-co-DM)S_E55 and CP(MH-co-DM)S_E77 was characterized by FT-IR and ¹H NMR.Then CP(MH-co-DM)S_E55 and CP(MH-co-DM)S_E77was added to the E51/methylhexahydrophthalic anhydride(Me HHPA)curing system to modify thermosets,and their influence on E51 curing kinetics,mechanical properties,thermal properties,dielectric properties and humidity-heat aging resistance with different loadings was systematically studied.The results indicated that the curing behaviors of the E51/Me HHPA system were not significantly affected by CP(MH-co-DM)S_E55.The flexural strength,modulus,and fracture toughness of CP(MH-co-DM)S_E55 modified thermosets were effectively improved,achieving both toughening and strengthening effects,and simultaneously increasing its T_g and thermal stability.With a loading of CP(MH-co-DM)S_E55-4 wt%,the overall mechanical properties of the modified thermosets were the best.Also,the dielectric performance and humidity-heat resistance of CP(MH-co-DM)S_E55 modified thermosets were improved,which delayed the thermal yellowing behavior and improve the maintenance degree of thermal mechanical properties after aging.2.Research on polysiloxane modified(3-4-epoxycyclohexane)3-4-epoxycyclohexyl carboxylate methyl ester(ECC)for LED electronic packagingFirst,CP(MH-co-DM)S_E79 was prepared using D₄,D₄H,TMDS,and EP-101 as raw materials.The chemical structure of CP(MH-co-DM)S_E79 was characterized by FT-IR and¹H NMR.Then CP(MH-co-DM)S_E79 was added to the ECC/Me HHPA curing system to prepare modified ECC thermosets,it exhibited excellent compatibility with ECC resin.Then,the influence on ECC curing kinetics,thermal properties,mechanical properties,shore hardness,dielectric properties,moisture resistance and humidity-heat aging resistance and optical transmittance durability of modified ECC thermosets with different CP(MH-co-DM)S_E79loadings were studied.The results indicated that the curing reaction of the ECC/Me HHPA system was promoted by the introduction of CP(MH-co-DM)S_E79.Compared to neat ECC thermosets,the mechanical properties of modified ECC thermosets with a CP(MH-co-DM)S_E79-15 wt%loading were the best,with flexural strength and impact strength increasing by 61%and 123%,respectively.At the same time,their initial thermal decomposition temperature was higher than that of neat ECC thermosets,but T_gs was reduced.In addition,the dielectric properties,humidity-heat resistance and optical transmittance durability of CP(MH-co-DM)S_E79 modified ECC thermosets had been improved,which were expected to be used in LED electronic packaging.